Molecular surveillance for dengue serotypes among the population living in Moyen-Ogooué province, Gabon; evidence of the presence of dengue serotype 1.

BACKGROUND: Despite dengue virus (DENV) outbreak in Gabon a decade ago, less is known on the potential circulation of DENV serotypes in the country. Previous studies conducted in some areas of the country, are limited to hospital-based surveys which reported the presence of some cases of serotype 2 and 3 seven years ago and more recently the serotype 1. As further investigation, we extend the survey to the community of Moyen Ogooué region with the aim to assess the presence of the dengue virus serotypes, additionally to characterize chikungunya (CHIKV) infection and describe the symptomatology associated with infections. METHOD: A cross-sectional survey was conducted from April 2020 to March 2021. The study included participants of both sexes and any age one year and above, with fever or history of fever in the past seven days until blood collection. Eligible volunteers were clinically examined, and blood sample was collected for the detection of DENV and CHIKV using RT-qPCR. Positive samples were selected for the target sequencing. RESULTS: A total of 579 volunteers were included. Their mean age (SD) was 20 (20) years with 55% of them being female. Four cases of DENV infection were diagnosed giving a prevalence of 0.7% (95%CI: 0.2-1.8) in our cohort while no case of CHIKV was detected. The common symptoms and signs presented by the DENV cases included fatigue, arthralgia myalgia, cough, and loss of appetite. DENV-1was the only virus detected by RT-qPCR. CONCLUSION: Our results confirm the presence of active dengue infection in the region, particularly DENV-1, and could suggest the decline of DENV-2 and DENV-3. Continuous surveillance remains paramount to comprehensively describe the extent of dengue serotypes distribution in the Moyen-Ogooué region of Gabon.

Microfilariae Prevalence and its Association with Anemia Among First-time Blood Donors in Lambaréné, Gabon

Background: Anemia remains a significant public health concern in Gabon, particularly among children, adolescents, and females. Gabon is also home to two major species of filarial worms, Loa and Mansonella spp., which cause microfilaremia. The epidemiological nexus between hemoglobin (Hb) concentrations and microfilaremia in Gabonese first-time blood donors remains unknown. Aims: To understand better the epidemiological relationship between anemia and microfilaremia to improve donor selection and management protocols. Study Design: A retrospective cohort study. Methods: This study was conducted among first-time blood donors in Lambaréné between March 2018 and October 2019. Participants aged 16-65 years old and weighing a minimum of 50 kg were enrolled using standard donor selection criteria. An automatic hematological analyzer was used to quantify Hb concentrations, and microscopy techniques were used to detect the presence of microfilariae. Results: Microfilariae were found in 4.8% (35/723) of the 723 first-time blood donors from Lambaréné. Anemia was classified as mild in 35.5% (257/723) and moderate in 1% (7/723). No significant associations were found between the distribution of microfilariae and variables such as age, sex, socioprofessional classification, marital status, or residence. Blood group O donors had a higher prevalence of microfilariae (6%) than non-O donors (2.7%). However, the observed difference was not statistically significant (AOR =2.3, p = 0.052). Furthermore, microfilariae were associated with increased moderate anemia (3.7% vs. 29%, AOR =15.6, p = 0.003). Conclusion: Our findings highlight microfilaremia as a possible etiological cause of anemia among Gabonese blood donors, emphasizing the need for further research and a potential review of donor management strategies.

Evaluation of HIV-1 rapid diagnostic tests in the context of viral genetic diversity in Libreville (Gabon).

Introduction: in order to promote rapid care of HIV-positive people and to reduce the human immunodeficiency virus (HIV) transmission in Gabon, the national screening algorithm is essentially based on rapid diagnostic tests (RDTs). However, most of these RDTs are not evaluated. Their sensitivities and specificities remain unknown locally. The aim of this study was to determine the diagnostic performance of 3 RDTs used for HIV-1> screening in Gabon. Methods: of the one hundred and sixteen (116) samples tested, 60 plasmas were HIV-1 positive with known genotypes and viral loads; 51 sera were HIV-1 negative while 5 had an undetermined serological status. All the samples were tested by quantitative RT-PCR (Gold standard) and by the following RDTs: Vikia, Alere Combo and Alere Determine. The sensitivities and specificities of the different RDTs were calculated using Epi Info version 6.04dfr. The level of agreement between tests was determined by Cohen´s Kappa test. Results: the three RDTs´ sensitivity according to HIV-1/M subtypes was 100% (95% CI: 92.6-100) while their specificities ranged from 94.6% (95% CI: 84.2-98.6) for the Vikia test to 96.4% (95% CI: 86.6-99.4) for the Alere Combo and Alere Determine tests, respectively. The concordances between the three RDTs were excellent with kappa values ranging from 0.931 (95% CI: 0.864-0.977) to 0.948 (95% CI: 0.890-1.00). Conclusion: the three RDTs showed a maximum sensitivity of 100% and specificities ranging from 94.6% to 96.4%. The specificities obtained with these RDTs are lower than those recommended by the WHO for their inclusion in an HIV-1 screening algorithm.